Histograms of relative orientations between and the iso-τ₃₅₃ contours towards Lupus. Histograms peaking at 90° and/or −90° correspond to predominantly perpendicular to iso-τ₃₅₃ contours. In contrast with Planck Collaboration Int. XXXV (2016), the error bars are estimated by sampling of a Gaussian polarization model, including – by construction – spatial correlations which are absent when considering simple Poissonian statistics.